In commercial vehicles, a common cause of lamp failure is bulb filament breakage. This is brought about by the continuous exposure of the lamp to severe shock and chassis vibration.
Numerous devices have been previously proposed, attempting to reduce such shock and vibration related failures. None has been fully successful, inasmuch as the frequencies and amplitudes of shock and vibration are too wide-ranged to permit simple solution. Most devices previously disclosed have had beneficial results regarding isolation of mild vibration, but severe shock isolation has only been accomplished heretofore by means which substantially defeated vibration isolation characteristics.
Shock tests for vehicle lamps are severe and range from an 18 inch - 60 lb. drop force at a frequency of 750 cycles/minute (SAE-J577) to a 25 G force load for 7 milliseconds (MIL-STD-202). Consequently, obvious methods of cushioning lamp bulb filaments are inadequate since considerable physical damage is caused under minimum test procedures.
An object of the present invention is the generation of lamp which offers resistance to bulb failure due to mild shock and vibration, while simultaneously resisting physical damage from high shock loads.
A further object of the invention is the provision of a suitable lamp which is relatively inexpensive to fabricate and may be readily assembled without the need for a complex procedure.